I-55 south to Memphis. US78 southeasterly to I-22/to Birmingham, AL. South on I-65 to Montgomery, AL. Then catch I-85 for a few miles east to exit #6 in Montgomery and south to catch US231 down through Dothan, AL to I-10. Head east on I-10 to exit #225 and head south on US19/US27 to where US27 splits off toward Ocala in Chiefland, FL.
Looks like a pretty easy route with minimal large cities. Plus you stay off I-75. US231 and US19 are four-lane highways with limited traffic. We take the above route from Birmingham to Crystal River, FL every year to & from MI. Plus there's a nice campground north of Troy, AL along US231 called Deer Run RV Park. FHUs, cable, paved pads and under $35 with Good Sam card.